Requirements for grounding welding of cable tray supports

Cable tray supports should be grounded using continuous conductive paths, with welding or bonding connections ensuring electrical continuity and compliance with NEC standards.

Overview of Cable Tray Grounding

Grounding cable tray supports is essential for safety, system reliability, and compliance. Proper grounding provides a low-impedance path for fault currents, protects personnel from electric shock, prevents equipment damage, and minimizes electromagnetic interference (EMI) in sensitive systems. All metallic cable trays must be grounded according to NEC Article 250.

96, regardless of whether the tray itself serves as an Equipment Grounding Conductor (EGC),.

Welding and Bonding Methods

Welded Connections: Welding can be used to bond cable tray supports to the grounding system, creating a permanent, low-resistance path. Ensure that the weld is clean, free of coatings, and fully penetrates the metal to maintain conductivity. Welding is particularly effective for steel or stainless steel trays and supports, providing mechanical strength and electrical continuity.

Mechanical Bonding: Where welding is not feasible, grounding clamps, bonding jumpers, or tin/zinc-plated connectors can be used to connect tray sections and supports. Each splice point or tray section should be bonded to maintain a continuous conductive path. For wire mesh trays, mechanical bonding is preferred because coatings or powder finishes can reduce conductivity at welded points.

Grounding Conductor Integration: If the tray does not meet the minimum cross-sectional area to serve as an EGC, a separate grounding conductor must be installed along the tray. The conductor should be sized according to NEC tables and securely bonded to each tray section or support.

Material Considerations

Aluminum Trays: Avoid bare copper conductors due to electrolytic corrosion; use insulated conductors with exposed bonding points. Steel or Stainless Steel Trays: Welding or mechanical bonding is effective; ensure corrosion protection if exposed to moisture. Wire Mesh Trays: Mechanical bonding with a grounding conductor is recommended to maintain continuity and prevent reduced current-carrying capability.

Best Practices

Ensure continuous grounding across all tray sections and supports. Remove coatings at bonding points for effective electrical contact. Verify electrical continuity after installation using appropriate testing methods.

Follow standards such as BS EN 61537 for tray systems and NEC Article 392 for grounding requirements. Avoid using trays as walkways or supports for personnel, as this can compromise both safety and grounding integrity. By following these methods, cable tray supports can be safely and effectively grounded, ensuring compliance, personnel safety, and reliable operation of electrical systems.